Microwave-assisted synthesis of optically active poly(amide-imide)s with benzophenone and L-alanine linkages

Rapid and highly efficient synthesis of poly(amide-imide)s was achieved und er microwave irradiation by using a domestic microwave oven from the polyco ndensation reactions of 4,4'-carbonyl-bis(phthaloyl-L-alanine) diacid chlor ide [N,N'(4,4'-carbonyldiphthaloyl)] bisalanine diacid chloride(1) with sev en aromatic diamine (2a-2g) in the presence of a small amount of a nonpolar organic medium that acts as a primary microwave absorber. Suitable organic media was o-cresol. The polycondensation proceeded rapidly, compared with the conventional melt polycondensation and solution polycondensation and wa s almost completed within 10 min giving a series of poly(amide-imide)s with inherent viscosities about 0.36-0.85 dl g(-1). The resulting poly(amide-im ide)s were obtained in high yield and were optically active and thermally s table. All of the above compounds were fully characterized by means of FTIR spectroscopy, elemental analyses, inherent viscosity (eta (inh)), solubili ty test and specific rotation. Thermal propel ties of the poly(amideimide)s were investigated using TGA/DTG. (C) 2000 Elsevier Science Ltd. All rights reserved.